Collar finder



April 14, 1964 D. U. SKINNER COLLAR FINDER Filed Apri1`11. 1961 2 Sheets-Sheet 1 ATTO/PNEVJ D. u. sKlNNER COLLAR FINDER April 14, 1964 2 Sheets-Sheet 2 Filed April l1. 1961 United States Patent O "i 3,128,828 COLLAR FINDER Derwood U. Skinner, Houston, Tex., assignor to Houston Uil Field Material Company, inc., Houston, Tex., a corporation of Delaware Filed Apr. 11, 1961, Ser. No. 102,235 4 Claims. (Cl. 166-214) The present invention relates to an improved collar finder particularly for use in locating collars of pipe disposed in a well bore.

In the drilling industry, it is frequently necessary to determine the exact depth of a particular collar which joins sections of pipe in the well bore, such as casing and the like. Previously, collar nders have been utilized which included a set of upwardly extending ngers or flipper dogs. These prior collar finders are lowered into the casing to the approximate depth of the collar to be located, and then pulled upwardly until the flipper dogs fall into the wider diameter area of a collar between two successive lengths of pipe, such as casing. Thereupon, the upward movement jams the ipper dogs against the bottom of the upper section of casing and this increase in drag while pulling upwardly is indicated on suitable indicating apparatus at the surface. To determine the exact depth of this collar it is necessary to note the exact length of the drill pipe, and the like, on which the collar nder is mounted. To release the collar finder, after the depth of the collar has been determined, additional force is applied to shear a pin which holds the flipper dogs in an extended position. Thus, the prior collar finders are essentially one-shot devices because they have to be completely removed from the well and the shear pin replaced before being of further use.

The present invention is directed to a device which is lowered by an operating string of pipe into the bore to the approximate location of the collar to be located. Thereupon a retaining means is disengaged from the device exposing flipper dogs yieldably biased in an extended position. The device is then pulled upwardly by raising the operating string until the flipper dogs engage the bottom of a section of casing at the collar which prevents further upward movement. Thereupon the exact depth of the collar is noted at the surface, in a conventional manner, by the sudden increase in tension or restraint in upward movement of the operating string of pipe. If the collar located is not the one sought, then the device may be lowered a short distance to re-engage the retaining means which retracts the previously extended flipper dogs. Thereupon, the device of the present invention may be raised or lowered and the device operated again to locate another collar. Thus, the present invention is immediately reusable and does not require a return to the surface before it is capable of locating further collars.

The only manipulation done at the surface with the present invention requires the lowering of the device of this invention on an operating string of pipe, rotating the pipe to disengage the retaining means and thus permitting extension of the ipper dogs, raising the operating string of pipe until the flipper dogs butt against the casing at the collar, and noting the length of operating pipe as an indication of the depth. The operating string of pipe is then lowered to re-engage the retaining means and to retract the flipper dogs therein. The operating string may then be raised or lowered to locate other collars, if desired, or the operating string may be raised to bring the device to the surface and out of the well bore.

Therefore, it is an object of the present invention to provide an improved collar finder which is immediately reusable and does not require a return to the surface before subsequent collars may be located.

3,128,828 Patented Apr. 14, 1964 ice Another object of the present invention is to provide an improved collar finder which utilizes retaining means which can be engaged and disengaged while the collar finder is in the bore to retract or to permit extension of the ipper dogs.

A still further object of the present invention is to provide an improved collar finder having at least one flipper dog pivotably mounted on the body and biased for outward movement, flipper dog retention means movably disposed about the body and arranged for movement about andaway from engagement with the flipper dog to release and retract the flipper dog.

Yet another object of the present invention is to provide an improved collar finder having a sleeve controlling the extension and retraction of the ipper dogs and in which the sleeve is engageable and disengageable with the body of the collar finder by an automatic coupling.

Another object of the present invention is to provide an improved collar iinder which is easy to manipulate, ruggedly efficient in use, and easy and relatively inexpensive to maintain and repair.

Other and further objects, features and advantages will be apparent from the following description of presently preferred embodiments of the invention, given for the purpose of disclosure, and taken in conjunction with the accompanying drawings, where like character references designate like parts throughout the several views and where:

FIGURE 'l is a partial sectional side view of a collar finder according to the present invention with the flipper dogs retracted while in a well bore,

FIGURE 2 is a View similar to FIGURE l with the flipper dogs extended `and the collar located,

FIGURE 3 is a view similar Ito FIGURE l, showing a modification of the invention in which an automatic coupling is -used to re-engage the shield,

FIGURE 4 is a view similar to FIGURE 3 with the flipper `dogs extended and the collar located, and

FIGURE 5 is Ia sectional view of the bow springs and limit stops taken along the line 5-5 of FIGURE 1.

In general the collar finder of the present invention comprises a mandrel or central body member adapted to be connected to an operating string of pipe, having at least one ilipper dog pivotably mounted on the mandrel and biased outwardly, and retaining means releasably engageable with and slideably mounted on the mandrel whereby the retaining means, when engaged with the flipper dog, holds it in a retracted position adjacent the mandrel and when released permits the flipper dog to extend. The present invention also contemplates an automatic coupling for re-engaging the retaining means with the mandrel in a position which retracts the ipper dog.

Referring now to the drawings and particularly to FIGURE l, the reference numeral 10 generally designates the collar nder shown within a section of casing 12 in a well bore (not shown) which is joined to an upper section of casing 14 by the collar 16 to be located. The collar finder 10 generally includes an elongate tubular mandrel 18 having at least one flipper dog 20 pivotally mounted thereon and the retaining means 22, here shown as a sleeve, slideably mounted about the mandrel 18. The collar finder 10 is conventionally attached in any desired manner, such as by screw threads 19, to a section of the operating string of pipe 24 at its upper end, and may include screw threads on its lower end for connection to additional devices 26 if desired. Thus, advantageously, the collar finder may form part of an uninterrupted string of pipe, such as drill pipe and the like. The mandrel 18 is here shown as a hollow cylinder having brackets 28 conventionally fastened thereto on its upper portion. The flipper dog 20 is pivotably mounted on the bracket 28 as by the pin 30 and is yieldingly urged or biased outwardly by the spring 32.

The retaining means is here shownas a generally cylindrical sleeve 22 slidably or telescopically mounted about the mandrel 18, and as shown in FIGURE 1, holds the flipper dog 20 in a retracted position adjacent the mandrel 18. The lower portion 34 of the sleeve 22 includes conventional internal threads which are engaged with similar external threads on a shoulder 36 conventionally attached, as by welding, to the mandrel 18. In this manner, the sleeve 22` is releasably engageable with the mandrel 18. It is, of course, obvious that the shoulder 36 need not be a separate part, but may be integral with the mandrel 18.

Mounted on-the outer periphery of the sleeve 22 in a suitable groove or recess 38 is a conventional bow spring 40 whichexerts a small resilient drag against the inner surface of the casing 12. The bow spring 4) is releasably attached to the sleeve 22 as by the screws 42. The upper portion of the bow spring 40 is held slideably adjacent the sleeve 22 by the lug 44. To obtain the maximum usefulness from the collar locator of the present invention, tap holes 46 and an additional lug 47 have been provided adjacent the recess 38 in the sleeve 22 so that a bow spring larger than the bow spring 40 may be mounted upon the sleeve 22 for use in casing larger than that shown as 12. Similarly longer flipper dogs than the flipper dog 20 may be pivoted on the mandrel 18.

Referring now to FIGURE 5, a sectional end view of the collar llnder is shown. Three bow springs 48 are mounted in the recesses 38 about the sleeve 22. These bow springs press outwardly against the casing 12 to provide a resilient drag and also serve to center the collar finder 10 within the bore. Also located on the sleeve 22 is at least one removable stop 48 which limits sliding movement of the sleeve 22 by butting against the shoulder 36 as will be hereinafter described.

Referring now to FIGURE 2, the collar finder 10 is shown after locating the collar 16 by butting the flipper dog against the lower end of the casing 14. To accomplish this, the mandrel 18 of the collar finder 10 is rotated within the casing 12 by rotating the operating string 24, with suitable apparatus at the surface, not shown. Since the bow springs 40 press outwardly against the casing 12, rotation of the mandrel 18 does not rotate the sleeve 22 which is held against rotation by the bow springs 40 engaging the inner wall of the casing 12 but rather unscrews the internal and external threads engaging the collar 36 and lower portion 34 of the sleeve 22. Thereupon, when the mandrel 18 is pulled upwardly, the disengaged sleeve 22 is held stationary against the casing 12 by the bow springs 40. The llipper dogs 20 are then released by the upward movement of the mandrel 18 and extend outwardly against the casing 12.

As the mandrel is pulled upwardly the flipper dogs 20 continue to bear outwardly against the casing 12. The sleeve 22 continues to remain stationary until the shoulder 36 engages the limit stop 48 and thereafter the sleeve 22 is pulled upwardly along with the mandrel 18.

The inside diameter of the collar r16 is larger than the linside diameter of the casing 12 and 14. When the mandrel 18 is moved upwardly with the flipper dogs 20 extended and pressing outwardly against the casing 12, the only resistance to upward movement is the drag of the flipper dogs 20 on the casing 12, the weight of the collar finder 10 and operating string 24, and the drag of the bow springs 40 against the casing 12 if the shoulder 36 has contacted the limit stop 48. When the extended end of the flipper dogs 20 pass the top part of the casing 12, then the springs 32 urge the flipper dogs 20 further outwardly so that they press against the collar 16. Further upward movement results in the flipper dogs 28 butting against the bottom part of the casing 14, thereby preventing further upward movement of the collar finder 10. This sudden increase in resistance to movement is conventionally noted at the surface and when the length of the 4 operating string 24 for the collar finder 10 is conventionally determined, the collar 16 is located.

If the collar which was located is not the one desired, then other collars, either above or below the one just located, may also be found. To find a lower collar, the collar nder 10, with the flipper dogs still extended, is simply lowered down the bore. The yieldingly urged flipper dogs 20 will retract so that they press again against the casing 12, or any other lower casing. The sleeve 22 will remain stationaryA until the mandrel 18 has telescoped therethrough and the screw threads on the shoulder 36 contact those on the lower portion 34 of the sleeve 22. Thereafter the sleeve 22 will be pulled downwardly with the mandrel 1S. To locate another lower collar. the collar finder, is simply raised again until the extended flipper dogs 20 butt the bottom of another section of casing at a collar.

To retract the flipper dogs 20, for removal of the collar finder 10 from the bore or to locate a collar higher than ythe collar 16 just located, the mandrel is again lowered until the screw threads on the shoulder 36 contact the screw threads on the lower portion 34 of the sleeve 22. This movement will retract (partially, if not completely, depending upon the particular design) the flipper dogs 2G so that the sleeve 22 holds them against the mandrel 18. Thereupon, rotation of the mandrel 18 will engage the screw threads so that the sleeve 22 again fully retracts the flipper dogs 20. As the bow springs 40 continue to press against the casing, rotation of the sleeve 22 will not occur until the screw threads are completely engaged. Now the collar finder 10 may be raised for removal from the bore, or to locate additional collars.

`Referring now to FIGURE 3, a modification of the present invention is shown having an automatic coupling thereon for re-engaging the sleeve 22 with the mandrel 118 when retracting the llipper dogs 20. The remainder of the collar finder 10 is as previously disclosed in FIG- URES l, 2, and 5. Attached to the lower portion of the sleeve 22, as by screw threads 60 is a slotted cylinder 62. The slotted cylinder 62 is a generally cylindrical tube having a number of slits 64 extending from the lower end thereof axially upwardly to the threads 60, thereby forming fingers 66. Internal threads 68 are placed on the lower end of the lingers 66. An internal shoulder 78 is located at the extreme lower end of the lingers 66. Attached to the mandrel 18is a shoulder 72 having external threads thereon to match the internal threads 68 on the slotted cylinder 62. The slotted cylinder 62 is made of a somewhat springy material, such as steel, and the slots 64 are cut therein to heighten this effect.

To utilize the collar finder 10 of FIGURE 3, the threads 68 on the slotted cylinder 62 are engaged with the threads on the shoulder 72. In this position, the sleeve 22 holds the flipper dogs 20 retracted adjacent the mandrel `18. To release the flipper dogs 20 for loeating a collar 16 between two sections of casing 12 and 14, the mandrel 18 is rotated. As before, the bow springs 40 press outwardly and prevent rotation of the sleeve 22 and slotted cylinder 62 attached thereto. Therefore, the threads 68 are disengaged.

Thereupon, as seen in FIGURE 4, when the mandrel 18 is raised, thesleeve 22 remains stationary so that the flipper `clogs 20 are released and extend outwardly until they contact the casing 12. Further upward movement 0f the mandrel 18 results inthe shoulder 72 butting against the sleeve 22 and thereafter the sleeve 22 is pulled up wardly along with the mandrel 18. The collar 16 is located, as hereinbefore described, when the llipper dogs 20 butt against the bottom of the casing 14 at the collar 16.

To retract the llipper dogs 20, `for locating further collars or for removal from the bore, the mandrel 18 is lowered smartly into the sleeve 22. yIn so doing, the threads on the shoulder 72 bear against the threads 68 on the lingers 66 and push them outwardly. This results 3 in the fingers 66 of the slotted cylinder 62 being sprung outwardly temporarily while the threads 63 act as a ratchet. For this purpose buttress threads are particularly suited for use as the threads 68.

Thereby, the mandrel 18 is re-engaged with the sleeve 22 and the ilipper dogs 20 are retracted, without the need -for rotation of the mandrel 18. To subsequently release the flipper dogs Ztl, it is only necessary to again rotate the mandrel 18, thereby disengaging the threads 68 and sleeve 22.

Thus, it is seen that the present invention provides a collar finder which is immediately reusable to locate -further collars -without the necessity of a return to the surface.

The present invention, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While presently-preferred embodiments of the invention have been given for the purpose of disclosure, numerous changes in the details of construction and the combination, shape, size and arrangement of parts may be resorted to Without departing from the spirit and scope of the invention as hereinafter claimed.

What is claimed is:

l. In a collar in'der for pipe in a well bore, an elongate mandrel, upwardly extending flipper dogs hinged at their lower ends on said mandrel, means yieldingly urging the upper ends of said ilipper dogs outwardly from said mandrel, said ipper ldogs when urged outwardly contacting said pipe, a sleeve mounted to slide on said mandrel adjacent and below said flipper dogs, thread means mounted on said mandrel, thread means mounted on said sleeve and engageable with said mandrel thread means, said sleeve holding said flipper dogs retracted adjacent said mandrel when said sleeve thread means are engaged with said mandrel thread means, said sleeve releasing said ipper dogs to `urge outwardly when the sleeve thread means are disengaged Ifrom the mandrel thread means and the mandrel is slid relative to the sleeve, said sleeve retracting said ilipper dogs when said sleeve thread means are re-engaged with the mandrel thread means, and movement retarding means mounted on said sleeve contacting said pipe.

2. rThe invention of claim 1 wherein said sleeve thread means are expandable whereby rotational movement of said mandrel 'disengages said sleeve and axial movement of said mandrel engages said sleeve.

3. In a collar finder for pipe in a well bore, an elongate mandrel, upwardly extending iiipper dogs pivotably mounted at their lower ends on said mandrel, springs yieldingly urging said -ipper dogs outwardly from said mandrel, said flipper dogs when urged outwardly contactable with ,said pipe and collar, a sleeve telescopically mounted on said mandrel, external threads on said mandrel, internal threads on said sleeve engageable with said external threads, said sleeve holding said ilipper dogs retracted adjacent said mandrel when both of said threads are engaged, said sleeve releasing said iiipper dogs to urge outwardly when both of said threads are disengaged land said sleeve is telescoped along said mandrel, and bow springs mounted on said sleeve `for engagement with said pipe to retard movement of said sleeve relative thereto.

4. The invention of claim 3 wherein said internal threads are mounted on expandable ngers of an axially slotted portion of said sleeve, whereby said internal threads are engageable with said external threads by axial telescopic movement of said sleeve relative to said mandrel.

References Cited in the le of this patent UNITED STATES PATENTS Re. 24,098 Bagnell Nov. 29, 1955 2,182,549 Brumbley Dec. 5, 1939 2,613,746 Whitney Oct. 14, 1952 2,741,316 Long Apr. 10, 1956 2,960,165 Schramm Nov. 15, 1960 

1. IN A COLLAR FINDER FOR PIPE IN A WELL BORE, AN ELONGATE MANDREL, UPWARDLY EXTENDING FLIPPER DOGS HINGED AT THEIR LOWER ENDS ON SAID MANDREL, MEANS YIELDINGLY URGING THE UPPER ENDS OF SAID FLIPPER DOGS OUTWARDLY FROM SAID MANDREL, SAID FLIPPER DOGS WHEN URGED OUTWARDLY CONTACTING SAID PIPE, A SLEEVE MOUNTED TO SLIDE ON SAID MANDREL ADJACENT AND BELOW SAID FLIPPER DOGS, THREAD MEANS MOUNTED ON SAID MANDREL, THREAD MEANS MOUNTED ON SAID SLEEVE AND ENGAGEABLE WITH SAID MANDREL THREAD MEANS, SAID SLEEVE HOLDING SAID FLIPPER DOGS RETRACTED ADJACENT SAID MANDREL WHEN SAID SLEEVE THREAD MEANS ARE ENGAGED WITH SAID MANDREL THREAD MEANS, SAID SLEEVE RELEASING SAID FLIPPER DOGS TO URGE OUTWARDLY WHEN THE SLEEVE THREAD MEANS ARE DISENGAGED FROM THE MANDREL THREAD MEANS AND THE MANDREL IS SLID RELATIVE TO THE SLEEVE, SAID SLEEVE RETRACTING SAID FLIPPER DOGS WHEN SAID SLEEVE THREAD MEANS ARE RE-ENGAGED WITH THE MANDREL THREAD MEANS, AND MOVEMENT RETARDING MEANS MOUNTED ON SAID SLEEVE CONTACTING SAID PIPE. 